Link budget: The total gain minus the total loss of a signal over a wireless link. Calculating a wireless link budget is required to determine if a wireless signal will reach the other side with enough strength for the receiver to reliably demodulate the signal.
Loss: A decrease in the power of a wireless signal, measured in dB. Loss can come from a variety of factors. A wireless signal will lose power as it travels through the air due to free space loss. Loss can also occur due to resistance in the cables connecting an antenna to a radio, from interference due to other radio signals or from environmental influences, such as trees, mountains, buildings or other objects.
Modulation scheme: A method of encoding digital data on an analog medium, such as a radio wave. Fixed wireless radios have variable modulations schemes, letting them to operate at differing data rates. Because more complex modulation schemes are more prone to error due to attenuation and interference, a radio will often fall back to less complex modulation schemes that are more resilient and robust. Although the link will be more reliable at lower modulation schemes, the throughput of the link naturally decreases. Radios we tested can dynamically adjust their modulation schemes according to changing RF conditions.
Receive sensitivity: The minimum signal level needed for a radio to detect a wireless signal. The received signal must be at least at this level for the radio to demodulate the signal. Generally, fixed wireless radios will support different modulation schemes, each of which has its own receive sensitivity.
Refraction: Describes the bending of a wave as it passes through an object. For instance, looking at a straw in glass of water will make the straw appear bent due to the refraction of light waves. Refraction is one way a signal can experience loss as it goes between two points.
